A combination weigher is one kind of a weighing apparatus which includes a plurality of weighing devices (weighers) and can perform combination calculation using weights of objects which are weighed by the weighing devices. In the combination calculation, a combination of weighing devices is selected, in which a combination weight of the objects which is formed by combination is closest to a target weight of the objects (not less than the target weight) and falls within an allowable range of the target weight (range between the target weight and an upper limit value of the target weight). A batch of the objects on the weighing devices selected in this way are taken to outside by a suitable method.
The above stated combination weigher is categorized into a fully-automatic combination weigher, a semiautomatic combination weigher, and a hand-operated combination weigher, depending on a feeding method of the objects to the weighing devices and a taking-out method of the objects from the weighing devices.
In the fully-automatic combination weigher, feeding of the objects to the weighing devices and taking-out of the objects from the weighing devices are performed in a fully-automatic manner.
In the semiautomatic combination weigher, only feeding of the objects to the weighing devices (or the corresponding feeding hoppers) is performed by an operator's hand operation (e.g., see Patent Literatures 1 and 2).
In hand-operated combination weigher, the feeding of the objects to the weighing devices and taking-out of the objects from the weighing devices are performed by an operator's hand operation (e.g., see Patent Literature 3).
In the case of products which are non-uniform in shape or are more likely to lose their shapes, a problem arises, if feeding of the products to the weighing devices and taking-out of the products from the weighing devices are performed in an automatic manner. As examples of products for which the automatic feeding of the products to the weighing devices and the automatic taking-out of the products from the weighing devices are not suitable, there are fresh products such as fishery products (sea food) (seasoned cod roe, salmon roe, herring roe, etc.) and agricultural products (asparagus, tomato, Japanese mizuna, etc.). For example, if a shape of the seasoned cod roe is lost in the automatic feeding and the automatic taking-out, its commercial value will be significantly impaired. Because of this, the hand-operated combination weigher is optimally used to fill such products into fixed-amount containers.